Conventionally, an electrostatic chuck disclosed in, for example, patent reference 1 is known as an electrostatic chuck. This electrostatic chuck includes a dielectric board having projections and recesses formed on the upper surface by embossing, an electrode formed inside the dielectric board, and an external power supply for applying a voltage to the electrode. Also, the top surface (substrate supporting surface) of each projection is covered with a conductor line. This conductor line electrically connects the substrate supporting surfaces of the projections, and the electrostatic chuck has a switch for grounding or floating the conductor line. Furthermore, those portions of the electrode which are close to the individual projections are removed in one-to-one correspondence with the projections.
The above-mentioned electrostatic chuck has as its main purpose to prevent the generation of particles by friction between a substrate and the projections, and prevents the electrostatic chucking force from acting between the substrate supporting surfaces of the projections and a substrate. That is, when holding a substrate by applying a voltage to the electrode, the substrate supporting surface of each projection and the lower surface of the substrate in contact with the substrate supporting surface are set at the same potential by moving electric charge through the conductor line, thereby preventing the Johnson-Rahbeck force from acting between them (see paragraph [0022] of patent reference 1). The substrate is held by the spatial Coulomb force between the recesses of the upper surface of the dielectric board and the lower surface of the substrate (see paragraph [0040] of patent reference 1). Also, when unloading the substrate, the substrate can be separated by rapidly moving electric charge by grounding the conductor line (see paragraph of patent reference 1).
Furthermore, in an electrostatic chuck disclosed in patent reference 2, an arrangement in which a separation mask has an insulating material such as diamond and a mask made of a metal such as titanium or titanium nitride is disclosed.    Patent reference 1: Japanese Patent Laid-Open No. 2004-22889    Patent reference 2: Japanese Patent Laid-Open No. 10-70180